from __future__ import annotations

from uuid import UUID

from sqlalchemy.dialects.postgresql import insert
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from models.points_ledger import PointsLedger
from models.user_points import UserPoints
from schemas.domain.points import ApplyPointsChangeCommand


class PointsRepository:
    def __init__(self, session: AsyncSession) -> None:
        self._session = session

    async def get_or_create_user_points_for_update(
        self, *, user_id: UUID
    ) -> UserPoints:
        insert_stmt = (
            insert(UserPoints)
            .values(user_id=user_id)
            .on_conflict_do_nothing(index_elements=[UserPoints.user_id])
        )
        await self._session.execute(insert_stmt)

        stmt = select(UserPoints).where(UserPoints.user_id == user_id).with_for_update()
        return (await self._session.execute(stmt)).scalar_one()

    async def has_ledger_event(self, *, user_id: UUID, event_id: str) -> bool:
        stmt = select(PointsLedger.id).where(
            PointsLedger.user_id == user_id,
            PointsLedger.event_id == event_id,
        )
        row = (await self._session.execute(stmt)).scalar_one_or_none()
        return row is not None

    async def append_ledger(
        self,
        *,
        command: ApplyPointsChangeCommand,
        balance_after: int,
    ) -> None:
        entry = PointsLedger(
            user_id=command.user_id,
            direction=command.direction,
            amount=command.amount,
            balance_after=balance_after,
            change_type=command.change_type.value,
            biz_type=command.biz_type.value if command.biz_type is not None else None,
            biz_id=command.biz_id,
            event_id=command.event_id,
            operator_id=command.operator_id,
            metadata_json=command.metadata.model_dump(mode="json", exclude_none=True),
        )
        self._session.add(entry)
        await self._session.flush()

    async def get_user_points(self, *, user_id: UUID) -> UserPoints:
        insert_stmt = (
            insert(UserPoints)
            .values(user_id=user_id)
            .on_conflict_do_nothing(index_elements=[UserPoints.user_id])
        )
        await self._session.execute(insert_stmt)

        stmt = select(UserPoints).where(UserPoints.user_id == user_id)
        return (await self._session.execute(stmt)).scalar_one()